Doesn't show admin page and all questions page

The link from WP dashboard leads me to /?post_type=question page and it just shows an error: “Nothing Found
It seems we can’t find what you’re looking for. Perhaps searching can help.”
I’ve edited questions.phph already like said in this topic: http://wordpress.org/support/topic/plugin-question-and-answer-forum-plugin-not-working-with-permalinks?replies=9
But still have this plugin broken.

http://wordpress.org/extend/plugins/question-and-answer-forum/